Calculate Area and Perimeter
Locate and measure the two parallel sides of the trapezoid (top base A and bottom base B).
Why: Trapezoids have exactly two parallel sides. These are different from each other in a true trapezoid, making both measurements essential.
Measure the perpendicular distance between the two parallel bases (not along the slant sides).
Why: Height must be perpendicular to the bases. Slant measurements give wrong results and overestimate area.
Use Area = (A + B) × h / 2 where A and B are the bases.
Why: The formula averages the two bases, then multiplies by height. This correctly calculates the area between parallel lines.
If needed, measure the two slant sides and add: Perimeter = A + B + side1 + side2.
Why: Perimeter requires all four sides. Without both slant sides, perimeter cannot be calculated accurately.
Check that Area is positive and record all measurements used.
Why: Documentation prevents recalculation. It also catches measurement errors where base or height seems unreasonable.
Trapezoidal Garden Bed
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